This invention relates generally to devices for imprinting information upon packages, cartons and the like as they travel successively spaced along the reach of a conveyor. More particularly, the invention provides an improved rotary carton marking device including an improved quick-coupled, friction driven inking wheel and a friction driven imprinting wheel provided with improved return mechanism automatically to bring the imprinting wheel to its starting condition upon release from the package and before the next package is intercepted.
Known devices capable of imprinting information upon packages, cartons and the like conveyed spaced along a given path along the reach of a conveyor are generally of complex construction with accompanying expense. Difficulty is encountered in establishing access for maintenance. With many devices of this type known to the art, the frequency of service rate is high due to high incidence of fatigue of many of the mechanisms and elements thereof. Known devices of this type have minimal versatility both as to the handling of articles of many different sizes and as to the orientation of the device for use with different conveyor systems.
Known devices generally were not compact and often were mounted to an open plate or the like so that they were subjected to much dust, grease and other foreign materials reducing their useful life, increasing downtime and increasing the frequency of repair and/or replacement.
Often different size or length packages are encountered in commercial use and an imprinting device which must be changed from package size to package size is not as commercially desirable as would an imprinting device easily adjustable for different size packages. Mounting of the article marking device on one side or the other of a conveyor, as well as positioning same to mark either the tops or bottoms of the packages demand versatility in mounting. Registration control is important and a marking device should be adjusted to effect registration of the imprint at a precise location upon the article without complexities and undue difficulty is highly desirable. Often access is difficult for making such adjustment.
Among other problems encountered with some known devices are difficulty in handling, as for removal and/or replacement of the inking wheel necessitating handling of the ink impregnated roller associated therewith; and difficulty encountered in returning the unit to a given orientation in relationship with the conveyor apparatus once the unit had been removed from its installed condition for maintenance and/or other servicing.
Another problem for which solutions have been offered by known devices of this general type involve the provision of mechanisms by which the rotary imprinting wheel positively is returned to a given starting position after each article moves beyond the imprinting wheel. Some conventional mechanisms involve use of tension springs expanded by the activity of the imprinting wheel and contractable to force the imprinting wheel to return. Cam and spring biased follower means also were suggested. One known device utilized a stationary latch means mounted on a fixed base and coupled to a roller movable with the imprinting wheel and having an endless spring coacting with said roller and the drive means for the imprinting wheel to be actuated in response to the rotation of the rotary roller for automatically positioning the roller and the drive means at a predetermined angular position so long as the drive means had been turned through a predetermined minimum initial increment by engagement thereof with the article moving along the conveyor.
The last mentioned device provided an endless spring which, in addition to being extended about a rotor rotatably movable with the imprinting wheel, that is the drive means therefor, and a shaft secured to a latch plate carrying latch means, the spring also is extended about a roller mounted upon a stationary mounting plate. The mounting plate carries upstanding pins which are positioned slidably to engage the spring whereby to provide an angular latching bias which is necessary to establish a positive latched starting condition. One considerable problem encountered during use of such known device involves rapid fatigue and wearing of the spring and pins. Flat portions are formed on both the spring and the pins.
The length of the article being imprinted determines the degree of rotation of the imprinting wheel. It is desirable that the imprinting wheel completes a revolution before engaging the next package. One reason for this is to reduce the wear on the inking means supplying ink to the imprinting means carried by said imprinting wheel. Where the wheel repeatedly returns to its start condition without completing a full revolution, wear is encountered at one location about said inking means.
Moreover, the rotation of imprinting wheel say through approximately 150.degree. to 180.degree. from its initial position, is required to assure that the spring is effective automatically to whip the wheel to its starting position. During rotation, positions are reached where the roller assumes a balance or null condition. Once the roller turns through the null position, the spring self-acts to force full rotation of the printing wheel. The influence of the spring is felt even where rotation has occurred through approximately 150.degree.. A minimum angular rotation of the printing wheel is required to return the wheel to its given starting position.
The location of the null condition is generally fixed and not adjustable, so that the minimum length of an article whose release is capable of returning the imprinting wheel to its given initial condition cannot be changed. It would be advantageous commercially to improve upon the versatility of such device by providing adjustment capability as to the minimum length of article with which the unit can be utilized, considerable reduction of fatigue upon the spring, improved versatility for use with conveyors moving at both slow and high speed, assurance of return to the given location with rotation of less than the assumed minimum degree of rotation and, as well, provide improvements to the construction and operation of the other components of such device leading to compactness so that minimal space is occupied at the conveyor, ease of operation and maintainence, reduction of costs and weight to enhance portability and to increase the ease of assembly, disassembly and adjustment, and to eliminate relative angular slippage of the imprinting means carried by the imprinting wheel as well as to materially reduce the tendency, encountered in many devices, of the imprinting wheel to be loosened during its frictional rotation.